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An Armored Amphibian That Lived Its Whole Life at Sea? It's a Fossil First
· Confirmed
In Short: Gerrothorax maritimus, named for its marine lifestyle, was about 74 centimeters long and had a flattened, armored body, making it a unique member of the amphibian lineage.
Researchers have identified Gerrothorax maritimus, a 237-million-year-old amphibian that lived its entire life in the sea, according to a study published in Nature Ecology & Evolution.
The fossils were discovered in Guizhou province, China, and date back to the Late Triassic period, a time when the area was a salty sea.
The researchers noted that modern amphibians do not live in fully marine environments due to their permeable skin, which cannot handle saltwater.
According to the study, Gerrothorax maritimus likely had a bottom-dwelling feeding strategy, similar to modern wobbegong sharks, and used its bony armor for protection against predators.
The team also conducted geochemical analysis on the fossils, finding strontium isotope ratios that matched those of Late Triassic marine environments.
Co-author Ryosuke Motani, a paleontologist at the University of California, Davis, said, “They would probably just wait at the bottom and then when prey comes around, they would just suck it in.”
Motani added, “This is potentially a revolutionary discovery.”
The discovery of Gerrothorax maritimus provides new insights into the evolution of amphibians and their ability to adapt to marine environments.
This finding challenges previous assumptions about amphibian habitats and highlights the importance of studying ancient ecosystems.
The research team believes that Gerrothorax maritimus lived in a marine environment and had a unique feeding mechanism that allowed it to thrive in saltwater.
The fossils were found by local farmers in Guanling County, in a layer of rock about 237 million years old, right in the middle of the Guizhou Triassic Fossil Sites.
What this adds
The geochemical analysis of the fossils provides strong evidence that Gerrothorax maritimus lived in a marine environment.
The discovery of Gerrothorax maritimus challenges the notion that amphibians are strictly tied to freshwater environments.
The research team's detailed analysis of the fossils offers a clearer picture of the animal's lifestyle and adaptations.
What's confirmed
- A newly identified 237-million-year-old amphibian fossil may be the first fully marine amphibian known to science.
- Read More: Two Students Named a New 309-Million-Year-Old Amphibian Relative After Their Mothers, Both Named Jean (Image Credit: Ryosuke Motani, UC Davis/ CC BY-NC-ND ) In the new study, the researchers note that over 8,000 species of modern amphibians exist, and none live in fully marine environments.
- “We’ve been mostly studying marine reptiles and the fish from this place, but now we also have this amphibian, and it’s a sort of very unusual member of the lineage.” The researchers have published their findings in Nature Ecology & Evolution and named the armored marine animal Gerrothorax maritimus.
- “If you think about today’s amphibians, this animal is unusual because it’s big,” Motani, who is a corresponding author on the study, said.
- "We've been mostly studying marine reptiles and the fish from this place, but now we also have this amphibian and it's a sort of very unusual member of the lineage," says co-author and paleontologist Ryosuke Motani, of the University of California, Davis.
What's still developing
- A newly discovered amphibian species called Gerrothorax maritimus was about 74 centimetres long and had a flattened, armoured body.
- There are more than 8,000 modern amphibian species, but none of them lives exclusively in a marine environment.
- The more complete specimen of the two fossils measures at least 73.7 cm (2.4 feet) along its preserved midline, though a handful of its tail bones are missing.
- "But these animals had their fingers preserved, so that means they probably died near where they lived."
- "It is unknown if stem amphibians all had permeable skin as in [modern amphibians], but even if they did, the body armor of Gerrothorax prevented water absorption through the skin, mandating water drinking and absorption from the digestive tract unlike in most extant amphibians," Diao and team write.
- That's pretty wild, given that the ability to traverse land and water is what amphibians are best known for.
- Researchers have identified Spea labreae, a previously unknown extinct spadefoot toad from La Brea Tar Pits and the first new species of extinct amphibian discovered from Ice Age Los Angeles.
- Alberto Cruz encountered it while reviewing La Brea Tar Pits’ relatively understudied collection of reptiles and amphibians.
- Only one other extinct Pleistocene amphibian has been reported from North America (a tree frog from Florida), making the find exceptionally rare and offering scientists a new window into the climate and environment of prehistoric Southern California.
- Researchers also identified the first known southwestern U.S. fossil record of the Mexican burrowing toad, Rhinophrynus.
- A tiny fossil overlooked for decades at La Brea Tar Pits has turned out to belong to a species previously unknown to science.
- They say it had a "flattened" body that was covered in bony armor, a potential defense mechanism against predators such as ichthyosaurs.